1. Field of the Invention
This invention relates to an improved shaped article made of a spandex polymer which contains polycarbonate soft segments. In particular, it relates to such an article made of a linear, segmented polyurethane-urea spandex polymer that has particular polycarbonate soft segments which impart improved chlorine and mildew resistance to the article.
2. Description of the Prior Art
Shaped articles, such as fibers and films, of spandex polymers are well known. Most commercial spandex polymers have "soft segments" of polyethers or polyesters. When these types of polymers are used for filaments that are incorporated into swimwear fabrics, the fabrics generally need improvement in resistance to degradation by swimming-pool chlorine. Such fabrics made with commercial polyester-based spandex filaments usually also need improvement in resistance to mildew.
Various polycarbonates have been disclosed for use in polyurethane polymers. However, these disclosures do not concern the chlorine and/or mildew resistance problems of spandex articles. For example, Lai et al, U.S. Pat. No. 4,131,731, discloses linear polycarbonates having terminal hydroxyl groups as being useful for reaction with organic isocyanates to form polyurethanes intended for coating materials. Rajan, U.S. Pats. No. 4,423,205 and 4,456,745, disclose polyurethane polymer made by reaction injection molding (RIM) techniques from the reaction product of (a) a polycarbonate glycol formed by heating a cyclic carbonate in the presence of a cationic initiator, (b) an organic polyisocyanate and (c) an organic chain extender having two isocyanate-reactive hydrogens. The polymer is reported to have good hydrolytic stability. Note that the aromatic diamines suggested by Rajan for the chain extension generally would be inadequate for commercial spandex filaments because of their very slow reaction with the isocyanates.
Muller et al, U.S. Pat. No. 3,509,233, discloses good hydrolytic stability for cross-linked or cross-linkable polyurethane elastomers which include polycarbonates based on 1,6-hexane diol and alkoxylated 1,6-hexane diol. Muller et al, U.S. Pat. No. 3,639,354, further discloses polyurethanes made with polycarbonates.
Semicarbazidoamines have been disclosed as chain extenders. For example, Rosendahl et al, U.S. Pat. No. 3,658,746, discloses such chain extenders for forming segmented polyurethanes in which the soft segment is a poly(hexane-1,6-carbonate). However, such polymers are known to discolor.
U.S. Pat. No. 3,994,881, Altau et al, discloses polyester polyurethane-urea spandex filaments having improved resistance to degradation by ultraviolet radiation and chlorine-containing bleaches, in which the hard segments contain ureylene groups which are joined to "functionally non-aromatic" radicals, at least 25 mol percent of which are of the formula ##STR1## The polymers are prepared from a polyester glycol, tetra-halogenated diisocyanates and tetra-halogenated diamines.
An object of this invention is to provide a shaped article of spandex having improved resistance to degradation caused by chlorine and/or mildew.